Protractor.



A. BRUBAKER.

PROTRAGTOR. APPLIOATION FILED APR. 19, 1910.

Patented Apr. 11, 1911.

HIIHHIHHII I'HI J0. g '2' Inventor.

- Witnesses I o Attorneys.

ABRAHAM BRUBAKER, OF WARSAW. INDIANA.

PBOTRAGTOR.

newer.

- Specification of Letters Patent,

lu tented .tpr. t r. tori.

App1ication filed April 18, 1910. Serial No. 556.310.

To all whom it may concern:

Be it known that l, Arman-cu lnn'nxiann, a citizen of the United States,residing at lN'a-rsaw, in the county of Kosciusko and State of Indiana,have invented a new and useful Protractor, of which the it'ollowing isaspecification.

This invention relates to protractors and its principal object is toprovide a simple device of this character having a novel arrangement ofdisks combined therewith and whereby very minute measurements may beobtained. i

Another object is to provide a protraetor which can be readily adjustedwithout the aid of separate devices and which can be convenientlymanipulated.

Nith these and other objects in view the invention consists of certainnovel details of construction and combinations of parts hereinafter morefully described and pointed out in the claims.

In the accompanying drawings the pre ferred form ofthe invention hasbeen shown.

In saiddrawings:Figure 1 is a plan 'view of the protractor. Fig. 2 is anenlarged section on line A-B of Fig. 1.

Referring to the drawings by characters of reference 1 and 2 designatetwo sides of a square the remote ends thereof being con- -'nected by anintegral plate 3 having straight outer edges. These sides and edges areall graduated to indicate inches and, prefer-- ably, fractions thereofdown to thinly-secmade, the graduation extending alonf both edges ofeach side 1 and 2. A segmental opening is formed within the protractor,

' said opening being outlined bythe arms 1 and 2-and by an arcuate inneredge 4 of plate 3 coneentmc with the angle 5 formed by the inner meetingedges of the arms 1 .;and 2.

located six inches trom the center o The arcuate edge 4 is preferablyand is marked as in degrees and half degrees: two sets of numerals beingpreteraldy associated with the gradnations so'that they can be larlyarranged in the member 2.

read from either end of the are. Anincision 6 is formed in the sidemember 1 and constitutes a; continuation of the edge 4-, this incisionextending one-degree into the side member. Another similar incision Tsimi- An incision 8 extends into the side member I.) at

the angle 5 and alines with the inner measurmg edge of the side member 1this incision being preferably onc-eighth of an inch in -theedge 4 undernormal conditions.

enough' to receive. a pointer.

A dish U is mounted on the member '3 and adjacent angle 5 amlwhen it isin its normal position the inner edge ol' member 1 extends radiallytherel'rom and the correspoinling-cdge of member :2 is disposed tangentthereto The pivot 10 oi the dislt is ecccntrically disposed and is inline with the inner edge of member 1. This pivot is removedone-sixteenth of an inch from the center of the disk and that p rtion ofthe periphery of the disk which is l'arthcst rcmoved 'l'rom the pivotnormally rests at the angle 5 and on the open end of incision 8. Thispoint on the periphery has been indi eated at 11 and is adapted to swingalong an arcuate line 12 o'l degrees. said line being subdivided intotwo equal parts one of which-has sixteen graduations.

- The Zero grmluation on the disk normally rests at the middlegraduation on the line ii. The said dish is graduated to indicate'l/ltr,

unit-hing needle or By arranging the dish 5) in the manner described itcan be'rotated -o as to recedc from the angle 5 and when the disk hasbeen given approximately a one quarter rotation, l/lt' of an inch of theincision 5% will have been exposed and addrd to the measuring rule. liystopping the zero graduation zit any one of the. grznluations on theline 12 a fraction of J ,/]t' inch can be measured along the incision 8from the angle .3. Obviously by turning the disk t) 180 degree theentire 'length of the incision R (l/t ol an inch) will be exposed.

A disk 13 is mounted on the side member 2 upon an eccentric pivot bl.said pivot and the center of the dish being in the arc of The said pivotis removed from the center 4, degree and the graduated are I?) alongwhich the disk swings extends 9t) dcgrees and is subdivided into 30parts. Obviously .bv shitting this dish any desired fraction of theincision T can be exposed so as to add any portion of a degree to the 90degrees described by the edge 4. For example. when the disk 1? is givena one-hall revolution, the incision 7 \vill be exposed its full lengthor one degree: should the disk be given a one quarter rotation or. inother words, moved through 90' degrees one half of the length. .\ll olthe incisions are just wide incision 7 will be exposed thus adding 30 tothe arcuate edge --l-. It will be apparent therefore that each of thethirty parts into which the 90 degrees are subdivided, desig nates 3degrees along the are but a movement oi the di k along the incision Tfor a distance equivalent of 1. Another disk 1(3- sinnlar in allrespects to the disk 13 is arranged upon the member 1 and cooperateswith the incision (3. v

In using the device it is necessary to employ a needle or similar markeror pointer having a very sharp point. If the first line is to he laidolt' degrees. 17 rods (scale 8 rods to the inch), the angle 5 is placedat the point of beginning and the side I 1 extended south. The needlepoint is placed at the graduation on line 4 which is 20 degrees 't'riundisk it; on side 1 and the protractor is then swung ahout angle 5 untildisk 'ltSa-omes against the needle. The permanent point can then beplaced 23;

inches from angle 5 along the graduated edge of arm 1. this distancebeing equal to 17 rods. It the next line is degrees, '15. Y, theprotractor is adjusted to the new point as before. the disk to heiugturned l5 degrees to the right. The pointer or needle is then placed atthe 30 degree graduation on the edge it and the protrzictor is swung tothe rightuntil the pointer contacts with the edge of the dirk-1t) whichwill he .dcgree within the incision (3. The

distance can then he pointed as before on the measuring rule. Should itbe necessary to utilize the disk t) to getthe exact distance,

a temporary point may he placed near the outer end of the memher 1 andthe disk 9 then turned the required distance. The protractor can then hepushed longitudinally of the memhc-r 'l. the temporary pointand thepoint at the angle 5-" acting as guides until one of the points strikesthe disk in the incision 8. The permanent point an then he placed.

lt is of course to he understood that vari they are adjusted.

'hat is claimed is:-

1. A protractor including a square, an arcuate portion concentriowiththe angle ol the square. there being incisions in the squareconstituting contimiations of the curved edge of the arcuate portion andof one/straight measuring edge of the square,

1 and adjustable means for varying the length of the exposed portion ofthe incision, f said means and square having cooperating i means forindicating the lengths of the me i posed portions of the incisions.

.\ n-otractor having an incision c0nstituting a continuation ofameasuring edge, and adj ustahle means for varying the length of theexposed portion of the incision and having means for indicating su chlength. protractor having an incision constitnting a continuation of ameasuring 1 edge. and an eccentrica lly mounted disk for varying thelength of the exposed portion I oi the incision.

4. protractor having an incision constituting a continuation of a masuring edge, and an eccentrically mounted disk for varying the. lengthof the exposed portion of the incision'there lieing cooperating meansvupon t the disk and protractor for indicating the 5 length of the.exposed portion of the slot.

5. A protractor including a square having a segmental opening theareuate edge of which is concentri with the angle of the .--quare. thereheing an incision constituting continuation of the arcuate edge, andmovable means for varying the length of the exposed portion of theincision. I t A protractor including a square having a graduated edge,there being an incision within the square and constituting acontinuation of the graduated edge for the reception of a markingelement, and a disk mounted for rotation about a point remote heing inalinement with the incision and with the, graduated edge and said diskbeing shittahlc to partly or entirely conceal the incision, v I

7. A protractor ineludinga square having a graduated edge, there beingan incision within the square and constituting a continuation of thegraduated edge for the reception of a marking element, and a diskmounted for rotation about a point remote from the center thereof. saidpivotal point, heingin alinement with the incision and with thegraduated edge and said disk heing shi'l'tahle to partly or entirelyconceal the incision. and eot'iperating means upon the square and diskfor indicating the length of the exposed portion of the incision.

In testimony that I claim the foregoing as my own, I have hereto atlixedmy signature in the presence ot two witnesses.

.UEILUTAM BRUBAKER; Witnesses:

MELVIN A. \VILCox, MAURICE WiLcox.

from the center thcreot. said pivotal point.-

